Various closures are known in the art for enclosing junctions in cables. The prior art closures suffer from the common drawback that they are relatively complicated in design, complicated to install, and accordingly unduly expensive. In addition, these closures have the further drawback that they are not easily adaptable for accommodating a wide range of junction and cable sizes, and accordingly, a craftsman needs to obtain numerous different closure sizes. In addition, end seals usable with such closures are generally not efficient or effective in keeping water out of the junction being enclosed.
Many of the above-noted drawbacks are eliminated in a design disclosed in EP0191609 (Raychem), which may be used with a cable splice case housing.
Accordingly, that prior document discloses a cable sealing apparatus, comprising:
a first end seal, the first end seal comprising:
a layer of precured gel, the gel being cured prior to contacting a cable to be sealed, the gel being elastic, conformable, having a cone penetration between 80 and 350 (10.sup.-1 mm), an ultimate elongation in excess of 50%, the gel preferably being disposed in a flexible matrix having an average volume of less than 0.01 inches.sup.3 with the gel preferably including a plurality of interconnected segments which lie within the interstices of the matrix, the gel further preferably being such that when the gel and matrix are stretched, the matrix reaches its ultimate elongation before the gel reaches its ultimate elongation; the layer of gel including means formed therein for passage of a cable therethrough between inner and outer opposite faces of the gel; and PA1 means forming an outer circumferential convoluted surface of the first end seal, the convolutions extending circumferentially around the end seal.
Since the gel creates an excellent moisture barrier against axial water propagation along an outer surface of the cable, and since the convolutions produce an excellent water barrier against water propagating down an outer surface of the end seal, excellent water isolation of a junction for any cable to sealed results.
Such an end seal is used where a cable splice is to be sealed against the environment. The splice may simply be a 1:1 in-line splice where two cables are joined end-to-end, or it may be a branched splice where two cables are joined to one, or where one cable is joined to an intermediate position along another. In each case an environmental seal, called a splice case, has to be built around the part of the cable or cables where cable jacket is missing. An end seal as described above is positioned around a cable at each side of the splice, and a cable splice case housing is provided that extends from one end to the other, bridging the splice between them.
In general, the circumferential surface of the end seal may be a surface of the gel, or may be provided by an outer casing having a convoluted outer surface.
The end seals are especially usable in closures for enclosing a splice along cables, in which case the assembly may further include a slit (and therefore "wrap-around") convoluted tube or other splice case housing for engagement with first and second end seals disposed on opposite sides of the splice. The convoluted tube engaging the end seals may have the additional features of being flexible, capable of stretching or contracting due to the convolutions, of being suitably crush resistant, and of being capable of being cut to any appropriate length in the field due to its uniform construction. Furthermore, it may be easily installable by simply prying open the slit thereof, and wrapping the tube around the cable. The term "wrap-around" is well known in the cable splice case art.